Self-Assembled Coatings for Magnesium Implants

Magnesium-based implants are gaining traction as a strong yet temporary way to surgically stabilize bone and connective tissue. The problem is that as the magnesium degrades inside the body it can cause an accumulation of hydrogen gas, which creates a cavity around the implant. Controlling the corrosion rate is crucial, especially in the first few days after surgery. Our coating dramatically reduces the degradation rate of magnesium-based devices. The coating also carries the benefit of customizable bioactive surface modifications — including drug delivery — for better tissue integration.

Description

Our novel anticorrosive coating is composed of self-assembled multilayer oganosilanes. This thin film forms spontaneously on the surface of an implant through layer-by-layer absorption. No new equipment is required. Also, the layered approach avoids the poor adhesion of one-step deposition coatings and the poor biocompatibility of conversion coatings. Through covalent bonds to the surface layer, molecules containing silane groups provide chemistry for attachment of small molecule drugs or for modifying hydrophobicity of the surface. To test the efficacy of our coating in mitigating hydrogen gas buildup, we implanted mice with both coated and uncoated magnesium discs and found that gas pockets formed around only the uncoated discs. Cell culture experiments demonstrated that our coatings are non-toxic and biocompatible.

Applications

- Improving performance of medical implants made of magnesium or magnesium alloy
- Hydrophobicity is particularly useful for cardiovascular applications
- Small molecule drug release

Advantages

- Self-assembling
- Anti-corrosive
- Improved biocompatibility and biointegration
- Easy to etch away to control the degradation of different parts of implanted devices

Invention Readiness

In vivo data

IP Status

https://patents.google.com/patent/US20210205503A1

Related Publication(s)

Patil, A. J., Jackson, O., Fulton, L. B., Hong, D., Desai, P. A., Kelleher, S. A., Chou, D.-T., Tan, S., Kumta, P. N., & Beniash, E. (2017). Anticorrosive Self-Assembled Hybrid Alkylsilane Coatings for Resorbable Magnesium Metal Devices. ACS Biomaterials Science & Engineering, 3(4), 518–529. https://doi.org/10.1021/acsbiomaterials.6b00585

Patil, Avinash & Fulton, Laura Beth & Sfeir, Charles & Beniash, Elia & Jackson, Owen. (2015). In-vitro cell culture study on Organosilane coated Mg discs. European cells & materials. 30. 51. 

Fulton, Laura Beth & Beniash, Elia & Patil, Avinash & Jackson, Owen & Sfeir, Charles. (2015). Self-assembling alkyl-silane anticorrosion coatings for resorbable Mg devices. European cells & materials. 30. 51.